1. Field of the Invention
This invention relates generally to a flocked filamentary element, and to fibrous structures formed from a plurality of said filamentary elements. More specifically, this invention relates to flocked filamentary elements including a major proportion by weight of substantially individualized cellulosic fibers of a papermaking length less than one-quarter inch (6.35 millimeters, and to fibrous structures, such as webs and yarns, suitable for use as substitutes for textile structures which include only textile-length fibers or continuous filaments.
The term "flock", "flocked" or "flocking", as used in describing the inventions set forth in this application, refers to the random adherence of the individualized cellulosic fibers, at any location along their lengths, to an adhesive layer on the surface of a core-strand, as well as to the adherence of only ends of such fibers to the adhesive layer in an aligned array.
2. Description of the Prior Art
Considerable activity has existed in the general area of flocking various substrates with substantially individualized fibers, as evidenced by the existence of numerous patents in this field. Much of this activity is unrelated to the field of textile substitutes which forms the subject matter of this invention.
The textile substitutes of this invention have an appearance simulating that of conventional textile structures that are formed from 100% textile-length fibers by conventional spinning, knitting or weaving operations. In addition, the textile substitutes of this invention have a balance of comfort factors; such as handfeel, drape, absorbency, elasticity and softness; along with the requisite strength to permit their use, either alone, or in combination with other elements, as towels, wipers, wearing apparel, cover materials for sanitary products such as diapers and sanitary napkins, and the like. Moreover, the textile-substitutes of this invention are inexpensive as compared to conventional textile structures made from 100% textile-length fibers, and therefore, can be adapted for either single, or limited use applications to compete in the disposable products market.
It has been suggested in U.S. Pat. No. 2,053,123, issued to Alles, to form an artificial thread including a high strength, high denier (175-275) core-strand flocked with short fibers, such as wood pulp. The artificial thread is used as a reinforcement for such materials as vulcanized rubber in the manufacture of tires. Alles suggests that the flocking associated with the core-strand provides better anchorage to the rubber than conventional yarns which are not flocked. This patent is concerned solely with achieving improved anchorage between the artificial threads and materials to be reinforced thereby. There is absolutely no suggestion of achieving a balance between appearance, strength, and comfort factors to form the textile substitutes of this invention. In fact, the high denier core-strand, while adequately serving as a high strength reinforcing member, does not provide the balance of comfort factors associated with the textile substitutes of this invention.
It has been suggested to form a scrim, or web product provided with a light fiber applique for use as a cover material for sanitary napkins. U.S. Pat. No. 2,900,980, issued to Harwood, and assigned to Kimberly-Clark Corporation, is one of several patents assigned to Kimberly-Clark which are representative of this type of construction. This construction has a soft surface feel as a result of the fiber applique; however, the major proportion by weight of the Harwood construction is the textile-length fibers forming the scrim. Therefore, this construction is more expensive to manufacture than a web product in which the major proportion of the fibers are relatively inexpensive cellulosic fibers of a papermaking length less than one-quarter inch (6.35 millimeters), such as wood pulp fibers and cotton linters. Moreover, the Harwood construction has a relatively low bulk,, and is therefore not suitable for use in applications in which high bulk is either required or desired. Also, and most important, the bonding at the junctions between the cross-laid threads making up the scrim of the Harwood construction tends to restrict relative movement between the threads at these bonded junctions. When the threads forming the scrim are close together (which is highly desirable to form an opaque web construction) the bonded junctions will also be close together and adversely restrict relative movement between the threads. This restriction in relative movement between the threads is evidenced by a higher initial modulus of elasticity than a conventional woven or knitted construction in which frictional movement between threads at their points of crossing is permitted to take place. The higher modulus is reflected in a stiffer product having less drape than a conventional woven or knitted construction.
A flocked web structure has also been suggested for use as an underlay for mats. U.S. Pat. No. 3,583,890, issued to Kolckmann, is representative of such a construction, and relates to an underlay which is placed between a mat and a deep-pile carpet to prevent slippage of the mat on the carpet. The underlay is in the form of a lattice-like structure formed from such materials as textile threads, paper threads, metal wires, and the like. This lattice structure is provided on one side with a non-slip coating, and on the other side with a flocking of textile fibers. The flocking is adapted to dig into the pile of the carpet to prevent slippage of a mat positioned on top of the underlay. This patent is concerned with preventing slippage between a mat and a deep-pile carpet, and is not at all concerned with achieving a balance of appearance, strength and comfort factors to form the textile substitutes of this invention. In fact, Kolckmann does not suggest parameters for the various components making up his lattice construction for achieving a balance among appearance, strength and comfort factors.
Flocked filamentary elements in the form of yarns are disclosed in U.S. Pat. Nos. 3,347,727 and 3,567,545, both of which are issued to Bobkowicz et al. These disclosures are devoid of any teaching of optimum quantities of components to achieve a balance among appearance, strength and comfort factors achieved in the textile-substitutes of the instant invention.
A discussion of yarns made by Bobkowicz is set forth in an article entitled, "Some Structural and Physical Properties of Yarn Made on the Integrated Composite Spinning System", appearing in Textile Research Journal, March 1974, Volume 44, Number 3, pp 206-213. The yarns disclosed in this article all include less than 50% by weight stable length fiber flock adhered by adhesive layers to multifilament core-strands having deniers of at least about 100. These yarns do not have a balance of strength and comfort factors achieved by the practice of applicant's invention.
It is suggested in British Pat. No. 1,228,325, assigned to Kendall, to provide an opaque web construction by including ultra short fibers, i.e., 50-300 microns in length, in a fibrous web of textile fibers. This patent does not suggest forming textile substitutes from any flocked filamentary elements, let alone filamentary elements including a preponderance of short, substantially individualized fibers of a papermaking length less than one-quarter inch (6.35 millimeters) and greater than about one millimeter. In fact, the ultra short fibers employed in the construction disclosed in the British patent are considerably shorter than the fibers which can be satisfactorily employed in the instant invention.